Johnson, 34, had said, leading into the Test, that he was thinking about retirement on "most days". On the same, Taylor commented that such a mind set was a sign that the end is near.
The left-armer endured a forgettable day with the ball on Sunday as Ross Taylor and Kane Williamson feasted upon some loose deliveries from Johnson, who finished the day with figures of 1/131 from 24 overs.
"Once you start thinking about giving the game away it's always a worrying sign, because days like Australia have had over the last day and a half, 130-odd overs in the field, they weigh heavily on you," Taylor was quoted as saying by cricket.com.au on Monday.
"You start to think, 'Should I still be playing, I'm now 34, the body's getting a bit older, I'm getting a bit sorer, do I still really want to do it?' That day yesterday would have really tested him. The good news is he got the wicket but if this is not his last Test, we're getting really close to seeing the last of Mitchell Johnson, which is a shame because he's been a terrific bowler for Australia."
At the end of New Zealand's first innings, Johnson had figures of 1/157 -- the most runs conceded by an Australian bowler in a Test innings at the WACA, surpassing Mitchell Starc's figures of 6/154 in 2012.
Johnson has played 15-and-a-half Tests without a five-wicket haul -- his last coming in the first Test in South Africa in February 2014.
"I think about it most days. It is probably getting to be that time, but to be honest I am just trying to play each game and enjoy it like I have said before. It could be after this game. I might just go 'I am done', but I'm still enjoying my cricket at the moment and enjoying the challenges," Johnson said after playing two days of the WACA Test.